Expandable seals/anchors have been described in U.S. Pat. No. 7,784,797. These designs were ring shapes of a relatively soft material that were pushed up a ramp surface to engage a surrounding tubular. One optional feature on such a design was the use of hardened buttons for penetration into the surrounding tubular. The buttons were disposed in an offset location from extending ribs that would also engage the surrounding tubular and could also optionally penetrate the tubular wall for additional anchoring. Seal material was disposed between ribs.
The issue that developed with this design was that although the anchoring feature into the wall of the surrounding tubular was adequate to retain the seal the small dimension of the carbide buttons limited the grip force on the assembly. Beyond that, the carbide buttons were mounted on a body that was relatively soft to reduce the required force for expansion of the seal assembly. Thus the ability of the carbide buttons to transmit an anchoring force to the mandrel were somewhat attenuated due to the relatively short intervening layer of the seal ring body.
Other expandable seals/anchors are described in U.S. Pat. Nos. 7,124,826; 7,367,404; 7,017,669; 6,564,870; 7,661,470; 7,367,404; 7,124,829; 7,954,516 and 7,779,924.
Another issue with the known design is that the setting sleeve was made of a relatively soft material to reduce the needed pushing force to get the sleeve to go up a ramped mandrel surface with the seal/anchor assembly to achieve the set position. These setting sleeves in the past were a cylindrical shape that had to also enlarge as it was pushed up the ramp. As a result relatively low yield steel structures were used for the setting sleeve. Such soft materials were not optimal in transferring an anchor force directly to the mandrel and in the past were not at all used for such function since the outer dimension on riding up the mandrel ramp was dimensioned to avoid engaging the surrounding tubular wall.
The present invention uses high yield steel for the setting sleeve and puts a weakening feature at the leading end to control the force needed to push the setting sleeve up the mandrel ramp. In one embodiment, a series of end axial slots are used to create a plurality of fingers that flex easily as they are driven up the ramp. These leading end fingers have a surface treatment on the exterior face that is designed to contact the surrounding tubular wall as or after the seal assembly ahead of the setting sleeve contacts the same surrounding tubular. The surface treatment can be wickers, hard particles or a roughening of the exterior surface in some other way. As a result the set position of the anchor/seal assembly is further locked in with the setting sleeve exterior surface wither abutting or penetrating the wall of the surrounding tubular at the same or a later time as the anchor/seal assembly making contact with the same tubular. These and other features of the present invention will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while understanding that the full scope of the invention is to be determined from the appended claims.